In recent years, a mobile phone can store a phonebook in which a phone number is associated with a name. The mobile phone displays information registered in the phonebook, such as callers' names and phone numbers of their outgoing calls or incoming calls. Callers may be registered in the phonebook during transmitting an outgoing call or receiving an incoming call. However, if the outgoing calls to the callers or the incoming calls from the callers are from non-registered callers in the phonebook, information other than the callers' phone numbers cannot be displayed.
If an incoming call is from a phone number not registered in the phonebook, a standard register name is automatically assigned to the phone number and the standard register name can be registered in the phonebook. In this manner, many phone numbers can be automatically registered in the phonebook. This may waste memory resources. More particularly, since an amount of memory allocated for the phonebook is usually limited, a new phone number cannot be registered in the phonebook if the memory size is deficient. The standard register name can be displayed during receiving a call after the name is registered in the phonebook; however, a user who receives the call will not have customized information or descriptions of the caller. Accordingly, there is a need for methods to provide custom information and mnemonics for a caller during a communication.